Aspects of Boundary Conditions for Nonabelian Gauge Theories

The boundary values of the time-component of the gauge potential form externally specifiable data characterizing a gauge theory. We point out some consequences such as reduced symmetries, bulk currents for manifolds with disjoint boundaries and some nuances of how the charge algebra is realized.Comment: 15 page

No news for Kerr-Schild fields

Algebraically special fields with no gravitational radiation are described. Kerr-Schild fields, which include as a concrete case the Kinnersley photon rocket, form an important subclass of them.Comment: 4 pages, Revtex

Some experiences in Electro-winning of Aluminium from fused Chloride bath

ALTHOUGH the electro-winning of aluminium from a fused chloride bath dates back to 1854, when Bunsen first isolated the metal, the interest in the process since then has been sporadic. Some of the earlier documenters like Mellor', Richards2, Borches3 and others had taken up the lead, but had been discouraged into branding the approach as impracticable. Patents filed by Aluminium Industrie A.G.4, I.G. Farben Industrie, A.G.5, Henriques and Thomsen6, Brode7, Treadwell8, Daudonnet9 and others during the period 1928 to 1931 indicated a resurgence of the chloride bath, although in the subsequent period the only mentionable patents were by Lovel and Phillips in 194510, Electronic Reduction Corporation in 1951,11 Grothe12 in 1953, and by Slatin13 in 1959 and 1963. Some of these were for the declared purpose of electroplating rather than electro-winning. The published investigations are also equally sporadic, and mention may be made of the work of Fink and Solanki14, Ramachandran15, and Newalkar and Altekar16

Twisted Gauge and Gravity Theories on the Groenewold-Moyal Plane

Recent work [hep-th/0504183,hep-th/0508002] indicates an approach to the formulation of diffeomorphism invariant quantum field theories (qft's) on the Groenewold-Moyal (GM) plane. In this approach to the qft's, statistics gets twisted and the S-matrix in the non-gauge qft's becomes independent of the noncommutativity parameter theta^{\mu\nu}. Here we show that the noncommutative algebra has a commutative spacetime algebra as a substructure: the Poincare, diffeomorphism and gauge groups are based on this algebra in the twisted approach as is known already from the earlier work of [hep-th/0510059]. It is natural to base covariant derivatives for gauge and gravity fields as well on this algebra. Such an approach will in particular introduce no additional gauge fields as compared to the commutative case and also enable us to treat any gauge group (and not just U(N)). Then classical gravity and gauge sectors are the same as those for \theta^{\mu \nu}=0, but their interactions with matter fields are sensitive to theta^{\mu \nu}. We construct quantum noncommutative gauge theories (for arbitrary gauge groups) by requiring consistency of twisted statistics and gauge invariance. In a subsequent paper (whose results are summarized here), the locality and Lorentz invariance properties of the S-matrices of these theories will be analyzed, and new non-trivial effects coming from noncommutativity will be elaborated. This paper contains further developments of [hep-th/0608138] and a new formulation based on its approach.Comment: 17 pages, LaTeX, 1 figur

Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity

In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact $(t - r)$ dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter $\sigma$. After that, we calculate the entropy associated to this noncommutative black hole solution. However the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.Comment: 19 pages, 5 figure

A Conformal Mapping and Isothermal Perfect Fluid Model

Instead of conformal to flat spacetime, we take the metric conformal to a spacetime which can be thought of as ``minimally'' curved in the sense that free particles experience no gravitational force yet it has non-zero curvature. The base spacetime can be written in the Kerr-Schild form in spherical polar coordinates. The conformal metric then admits the unique three parameter family of perfect fluid solution which is static and inhomogeneous. The density and pressure fall off in the curvature radial coordinates as $R^{-2},$ for unbounded cosmological model with a barotropic equation of state. This is the characteristic of isothermal fluid. We thus have an ansatz for isothermal perfect fluid model. The solution can also represent bounded fluid spheres.Comment: 10 pages, TeX versio

SYNTHESIS AND STRUCTURAL STUDIES OF 1-[(8-NITRONAPHTHO[2,1-B]FURAN-2-YL) CARBONYL] PIPERIDINE

Naphtho [2,1-b] furan-2-carboxyazide has been synthesized from ethyl 8-nitronaphtho [2,1-b] furan-2-carboxylate, by first converting into 8-nitronaphtho [2,1-b] furan-2-carboxyhydrazide , followed by diazotization. The reaction of carboxyazide with piperidine resulted in nucleophilic substitution reaction giving 1- [(8-nitronaphtho [2, 1-b] furan-2-yl) carbonyl] piperidine (NNFCP). The compound has been characterized by FT-IR, 1HNMR, Mass spectral data and X-ray diffraction analysis

Evolution of Holographic Entanglement Entropy after Thermal and Electromagnetic Quenches

We study the evolution and scaling of the entanglement entropy after two types of quenches for a 2+1 field theory, using holographic techniques. We study a thermal quench, dual to the addition of a shell of uncharged matter to four dimensional Anti-de Sitter (AdS_4) spacetime, and study the subsequent formation of a Schwarzschild black hole. We also study an electromagnetic quench, dual to the addition of a shell of charged sources to AdS_4, following the subsequent formation of an extremal dyonic black hole. In these backgrounds we consider the entanglement entropy of two types of geometries, the infinite strip and the round disc, and find distinct behavior for each. Some of our findings naturally supply results analogous to observations made in the literature for lower dimensions, but we also uncover several new phenomena, such as (in some cases) a discontinuity in the time derivative of the entanglement entropy as it nears saturation, and for the electromagnetic quench, a logarithmic growth in the entanglement entropy with time for both the disc and strip, before settling to saturation.Comment: 30 pages, 19 figures. Corrected typos and added some discussion. To appear in New J. Phy

The equations of fit in general relativity

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